U.S. patent application number 11/260521 was filed with the patent office on 2006-03-02 for user-retainable temperature and impedance monitoring methods and devices.
Invention is credited to Matthew Bloom, WM. Leroy Heinrichs, Gregory T.A. Kovacs, David Salzberg.
Application Number | 20060047218 11/260521 |
Document ID | / |
Family ID | 29214711 |
Filed Date | 2006-03-02 |
United States Patent
Application |
20060047218 |
Kind Code |
A1 |
Bloom; Matthew ; et
al. |
March 2, 2006 |
User-retainable temperature and impedance monitoring methods and
devices
Abstract
A user-retainable monitoring system is disclosed. At least a
pair of sensors is provided in association with a support member.
The support member is preferably of a type that may be worn by or
at least temporarily implanted in a patient. Possible sensor types
include temperature sensors and impedance sensors. Temperature
sensors may be used to detect a temperature differential between
areas of tissue indicative of pathology. Impedance sensors are used
to detect subcutaneous fluid detection. The support member may take
the form of a bandage, drain or other structure. Monitor structures
as described may have stand-alone utility or be connected to a
processor or data recorder to enable various functions.
Inventors: |
Bloom; Matthew; (Palo Alto,
CA) ; Heinrichs; WM. Leroy; (Menlo Park, CA) ;
Kovacs; Gregory T.A.; (Stanford, CA) ; Salzberg;
David; (Glen Allen, VA) |
Correspondence
Address: |
BOZICEVIC, FIELD & FRANCIS LLP
1900 UNIVERSITY AVENUE
SUITE 200
EAST PALO ALTO
CA
94303
US
|
Family ID: |
29214711 |
Appl. No.: |
11/260521 |
Filed: |
October 26, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10125051 |
Apr 17, 2002 |
6963772 |
|
|
11260521 |
Oct 26, 2005 |
|
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Current U.S.
Class: |
600/547 ;
128/903; 600/549 |
Current CPC
Class: |
A61B 5/413 20130101;
A61B 5/445 20130101; A61B 5/01 20130101; A61B 5/0031 20130101; A61B
5/0535 20130101 |
Class at
Publication: |
600/547 ;
600/549; 128/903 |
International
Class: |
A61B 5/05 20060101
A61B005/05; A61B 5/00 20060101 A61B005/00 |
Claims
1.-38. (canceled)
39. A device for monitoring a condition of a subject, said device
comprising: a support member; and one or more sensing portions
supported by said support member, wherein said one or more sensing
portions comprise at least one of: an impedance sensor and two
temperature sensors, wherein at least a portion of said device is
adapted to be implantable in the body of said subject.
40. The device of claim 39, further comprising electronic hardware
connected to said one or more sensing portions.
41. The device of claim 40, wherein said electronic hardware
includes one or more of an indicator for communicating information
based on data from said one or more sensing portions; a telemetry
or transmission unit; a memory unit; hardware for data acquisition
from said one or more sensing portions; and a power source for said
one or more sensing portions.
42. The device of claim 39, further comprising a programmed
processor.
43. The device of claim 42, wherein said programmed processor is
adapted to effect storage of data from said one or more sensing
portions; to effect analysis of data from said one or more sensing
portions; to effect a secondary medical procedure based on data
from said one or more sensing portions; or to produce a
notification signal based on data from said one or more sensing
portions.
44. The device of claim 39, wherein said support member is
tubular.
45. The device of claim 39, wherein said support member is a shunt,
a graft, a drain, a prosthesis or a catheter.
46. The device of claim 39, wherein the entire support member is
adapted to be implantable in the body of said subject.
47. The device of claim 39, wherein said one or more sensing
portions comprise two temperature sensors.
48. The device of claim 47, wherein said two temperature sensors
are spaced-apart a distance on said support member sufficient to
obtain measurements of a wound comprising area using one of the
temperature sensors and measurements of an adjacent
non-wound-comprising area of said subject using another temperature
sensor.
49. The device of claim 39, wherein said one or more sensing
portions comprise an impedance sensor.
50. The device of claim 49, wherein said impedance sensor is
supported by said support in a manner sufficient to position a
portion of said impedance sensor adjacent a first side of a wound
of said subject and a different portion of said impedance sensor
adjacent a second side of said wound.
51. The device of claim 39, wherein said one or more sensing
portions comprise an impedance sensor and two temperature
sensors.
52. A device for monitoring a condition of a subject, said device
comprising: a user-retainable support member comprising a
sensor-supporting adhesive region and a sensor-supporting
non-adhesive region, one or more sensing portions supported by said
sensor-supporting adhesive region and one or more sensing portions
supported by said sensor-supporting non-adhesive region, wherein
said one or more sensing portions comprise at least one of: a
portion of an impedance sensor and a temperature sensor.
53. The device of claim 52, wherein said user-retainable support is
a patch, bandage, strip, wrap, sleeve or bracelet.
54. The device of claim 52, wherein said one or more sensing
portions of said adhesive region comprise a first temperature
sensor and said one or more sensing portion of said non-adhesive
region comprise a second temperature sensor.
55. The device of claim 54, wherein said first and second
temperature sensors are spaced-apart a distance on said
user-retainable support member sufficient to obtain measurements of
a wound-comprising area using one said first temperature sensor and
measurements of an adjacent non-wound-comprising area of said
subject using said second temperature sensor.
56. The device of claim 52, wherein said one or more sensing
portion of said adhesive region comprises a first electrode of an
impedance sensor and said sensing portion of said non-adhesive
region comprises a second electrode of said impedance sensor.
57. The device of claim 52, further comprising electronic hardware
connected to said one or more sensing portions.
58. The device of claim 57, wherein said electronic hardware
includes one or more of an indicator for communicating information
based on data from said one or more sensing portions; a telemetry
or transmission unit; a memory unit; and hardware for data
acquisition from said one or more sensing portions.
59. The device of claim 52, further comprising a programmed
processor.
60. The device of claim 59, wherein said programmed processor is
adapted to effect storage of data from said one or more sensing
portions; to effect analysis of data from said one or more sensing
portions; to effect a secondary medical procedure based on data
from said one or more sensing portions; or to produce a
notification signal based on data from said one or more sensing
portions.
61. A device for monitoring a condition of a subject, said device
comprising: a user-retainable support member comprising a
non-adhesive region positioned between a first adhesive region and
a second adhesive region; and at least one sensor supported by said
user retainable support member, wherein at least a part of said
sensor is positioned at said first adhesive region and at least a
part of said sensor is positioned at said second adhesive
region.
62. The device of claim 61, wherein said sensor comprises a first
electrode and a second electrode and said first electrode is
positioned at said first adhesive region and said second electrode
is positioned at said second adhesive region.
63. A system for monitoring a condition of a subject, said system
comprising first and second sensing structures, wherein each
sensing structure comprises a support member and one or more
sensing portions supported by said support member, wherein said one
or more sensing portions comprise at least one of: an impedance
sensor and two temperature sensors.
64. The system of claim 63, wherein said one or more sensing
portions of said first sensing structure comprises a first
temperature sensor and said one or more sensing portions of said
second sensing structure comprises a second temperature sensor.
65. The system of claim 63, wherein said first temperature sensor
is capable of obtaining the internal body temperature from a non
wound-comprising reference area of a subject and said second
temperature sensor is capable of obtaining the temperature of a
wound-comprising area of said subject.
66. The system of claim 63, further comprising electronic hardware
connected to said one or more sensing portions.
67. The system of claim 66, wherein said electronic hardware
includes one or more of an indicator for communicating information
based on data from said first and second temperature sensors; a
telemetry or transmission unit; a memory unit; hardware for data
acquisition from said one or more sensing portions; and a power
source for said one or more sensing portions.
68. The system of claim 63, further comprising a programmed
processor.
69. The system of claim 68, wherein said programmed processor is
adapted to effect storage of data from said one or more sensing
portions; to effect analysis of data from said one or more sensing
portions; to effect a secondary medical procedure based on data
from said one or more sensing portions; or to produce a
notification signal based on data from said one or more sensing
portions.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to tissue monitoring,
especially with apparatus suited for sustained or continued use by
patients. Certain applications address concerns with wound healing
including infection and subcutaneous fluid build-up, another
addresses inflammation as in transplant rejection.
BACKGROUND OF THE INVENTION
[0002] Fluid accumulation and infection at the site of a wound can
significantly hinder wound healing. Fluid accumulation can exert a
detrimental mass effect upon adjacent tissue and compress vital
anatomy or structures. Infection can result in tissue morbidity,
rejection, fever, gangrene and even death.
[0003] Background discussion regarding fluid accumulation and
tissue infection follows, in turn. That certain information is
presented as background herein should not, however, be taken as
indication that the present invention does not predate it.
[0004] With respect to fluid accumulation, if detected before
significant damage occurs, it can often be treated by simple
surgical intervention. For instance, lancing and/or drain insertion
or implantation may provide adequate and continuing therapeutic
relief.
[0005] Impedance measurement has been employed to measure
volumetric changes of the body in certain applications. U.S. Pat.
No. 4,805,621 to Heinze et al. discloses a system adapted to
measure body tissue impedance, particularly to set the rate of a
pacemaker by reference to volumetric measurement of a beating heart
and thorax during respiration movement. Heinze neither discloses or
suggests the use of local impedance differences to locate or
monitor indicia negative of proper wound healing.
[0006] Regarding infection, it is well established that infection
can be effectively treated by antibiotics. Also, antibiotics can be
effectively administered prophylactically to avoid infection.
However, this approach may not be desired for reasons ranging from
drug interaction, to bacterial resistance to antibiotics.
Regardless, it is desired and often necessary to repeatedly check,
examine or monitor an area for infection--especially prior to
administering antibiotics.
[0007] It is also known that infected tissue presents at a higher
temperature relative to uninfected tissue. U.S. Pat. No. 6,135,968
to Brounstein teaches the use of temperature sensors affixed to an
insulative support to fit over or be adhered to a probe (such as a
finger) for accessing internal body locations via body orifices to
effect temperature-based examinations. The preferred embodiments
include two discrete temperature sensing regions allowing for
comparative analysis of tissue temperature. As stated in the
patent, an important function of the temperature sensor support in
all embodiments of the invention is to insulate a temperature
sensing patch from the fingertip of the user and thereby improve
the accuracy of the sensed temperatures by isolating temperature
sensed by the sensing patch from the influence of heat emanating
from the user's fingertip. Closed cell polyurethane foam with a
thickness of about 1 to 2 millimeters is disclosed as a suitably
pliable and insulative material for the temperature sensor
support.
[0008] By comparing the temperature of near-by healthy tissue with
that of a suspect site, a diagnosis can be made as to the existence
of abnormal subsurface tissue activity such as the growth of
malignant tumors, benign neoplasms, infections and/or
inflammations. The devices involved and examination techniques
disclosed are, however, by no means suited for long-term infection
monitoring.
[0009] One recently disclosed device is, however, suited for
sustained monitoring of wounds for infection. In a Nov. 5, 2001
issue of Medical Industry Today, a story was run reporting that the
University of Rochester had taken steps toward creating a bandage
that will change color depending on what kind of bacteria may be
present in a wound. The bandage was disclosed as capable of giving
an instant diagnosis as to whether the wound may require special
care or what kind of antibiotics would work best in treating it. A
silicon-based sensor is employed to differentiate between
Gram-positive and negative bacteria. Indication of further
application include similar sensors to identify several other types
of bacteria, with particular focus on research directed toward
antibiotic resistant strains. As embodied in a "smart bandage," the
sensor is said to function in connection with a type of molecule
called "lipid A" on the surface of Gram-negative bacteria. When a
complementary molecule linked to or part of the sensor binds to
lipid A, the sensor changes color.
[0010] The article indicates that color change of the sensor is
subtle and could be missed by a human eye. Accordingly, reading by
an ancillary device is discussed. One embodiment envisioned for the
bandage includes an array of dozens of different bacterial sensors
that will change color dramatically enough so a glance inspection
will alert the user to a serious infection.
[0011] Potential non-medical applications are also disclosed in
which, for example, a drinking vessel or wrapping around a package
of ground beef would change color to caution a user in the event of
the presence of certain bacteria. Further potential applications
envisioned include providing early warning against biowarfare.
[0012] The breakthrough described in association with the
development of the bandage was detecting and identifying a single,
distinct species of bacteria. Further development possibilities
were linked in the article to finding molecules that detect other
bacteria. In any case, the silicon sensors only have
bacteria-specific wound monitoring capability. Furthermore, even if
the prophesized sensor arrays come into being, they will only
detect such forms of bacteria corresponding specifically to the
array elements. Accordingly the smart bandage approach taught in
the article lacks general applicability. To remedy this, the
article merely suggests searching for molecules capable of
detecting other bacteria to add functionality in a piecemeal
fashion.
SUMMARY OF THE INVENTION
[0013] The present invention is geared toward broad-based detection
of wound and/or implant-related complications. Sensors registering
local temperature differences give indication of infection.
Temperature sensing aspects of the invention also find use in
monitoring other conditions such the progression to completeness of
normal wound healing, the state of anesthetized tissue, local
immune responses to vaccinations, the flow of blood to muscle flaps
or other tissues and the margins of viability of tissues affected
by bums or frostbite. Impedance sensing provides indication of
fluid build up or the volumetric status at a site. Such methodology
may be used in monitoring for post-surgical hematomas, and proper
functioning of devices such as shunts, grafts and drains.
[0014] In serving each such use, the present invention integrates
sensors formats that are amenable to prolonged retention by a
patient. Holding the sensors in close anatomic association with a
subject or patient for an extended period through the use of an
easily-retainable support allows for constant or periodic
monitoring by a patient, physician or other care provider.
[0015] User retainable formats include support structures suited
for external as well as internal use. In addition to those
described herein, further uses, advantages and features
distinguishing the present invention may also be apparent to those
with skill. The various apparatus as well as associated methodology
described herein form aspects of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Each of the following figures provides examples
diagrammatically illustrating aspects of the present invention.
Like elements in the various figures are indicated by identical
numbering. For the sake of clarity, some such numbering has been
omitted.
[0017] FIGS. 1A-1D show views of various sensor types as may be
used in the present invention.
[0018] FIGS. 2A-2J show views of various support member types as
may be used in the present invention.
[0019] FIGS. 3-6 show monitors according to the present invention
in use.
DETAILED DESCRIPTION
[0020] In describing the invention in greater detail than done
above, the subject monitoring system and underlying technology are
addressed first, followed by examples of apparatus produced
according to the present invention and associated methodology.
Before the present invention is described in such detail, however,
it is to be understood that this invention is not limited to
particular variations set forth and may, of course, vary. Various
changes may be made to the invention described and equivalents may
be substituted without departing from the true spirit and scope of
the invention. In addition, many modifications may be made to adapt
a particular situation, material, composition of matter, process,
process step or steps, to the objective, spirit and scope of the
present invention. All such modifications are intended to be within
the scope of the claims made herein. Furthermore, where a range of
values is provided, it is understood that every intervening value,
between the upper and lower limit of that range and any other
stated or intervening value in that stated range is encompassed
within the invention. The upper and lower limits of these smaller
ranges may independently be included in the smaller ranges and is
also encompassed within the invention, subject to any specifically
excluded limit in the stated range. Where the stated range includes
one or both of the limits, ranges excluding either both of those
included limits are also included in the invention. Also, it is
contemplated that any optional feature of the inventive variations
described herein may be set forth and claimed independently, or in
combination with any one or more of the features described
herein.
[0021] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
any methods and materials similar or equivalent to those described
herein can also be used in the practice or testing of the present
invention, the preferred methods and materials are described. All
existing subject matter mentioned herein (e.g., writings,
publications, patents, patent applications and hardware) is
incorporated by reference herein in its entirety. The referenced
items are provided solely for their disclosure prior to the filing
date of the present application. Nothing herein is to be construed
as an admission that the present invention is not entitled to
antedate such material by virtue of prior invention.
[0022] Also, it is noted that as used herein and in the appended
claims, the singular forms "a", "and," "said" and "the" include
plural referents unless the context clearly dictates otherwise.
Conversely, it is contemplated that the claims may be so-drafted to
require singular elements or exclude any optional element indicated
to be so here in the text or drawings. This statement is intended
to serve as antecedent basis for use of such exclusive terminology
as "solely," "only" and the like in connection with the recitation
of claim elements or the use of a "negative" claim
limitation(s).
[0023] Variations of the present invention include temperature
and/or impedance sensors provided in connection with a support
element or member. The present invention takes forms that the a
patient may wear (e.g., a bandage, strip, pad or patch, sleeve,
bracelet, suction cup(s) or wrap) or retains internally (e.g., a
shunt, catheter, drain or prosthesis), possibly by implantation.
The form-factor employed determines whether monitoring is
accomplished at or near the surface of the patient's skin or within
the patient's body. Both the format of the apparatus and associated
sensors may be configured to monitor for infection, near-by fluid
accumulation or other indica. Continued use by a patient for
(several) minutes, on the order of hours, days, weeks or longer is
contemplated with the present invention. Use for an extended period
of time is contemplated. Sometimes, a monitor according to the
present invention will be worn or retained by a patient for up to
60 days or longer (as in the case of permanent or semi-perminent
implants).
[0024] Before describing the various forms the invention may take,
together with applications they are suited for, optional sensor
types are first described. As shown in FIG. 1A, an impedance sensor
2 is provided using simple electrical leads 4. A proximal end 6 of
each such sensor member is typically connected to a diagnostic
instrument. Exemplary instruments, or components thereof, such as
described in U.S. Pat. No. 4,805,621 to Heinze et al.; U.S. Pat.
No. 4,837,501 or U.S. Pat. No. 5,068,618, each to Fry et al. or
other circuitry able to measure body tissue impedance may be used
in connection with these sensor members.
[0025] In operation, AC current or voltage is applied through the
leads via a pre-defined spectrum of frequencies or selected single
frequencies as needed. For impedance sensor variations of the
invention, there will always be at least two electrodes, since one
needs a source and sink for current (in this case, alternating
current).
[0026] Changes of the impedance of tissue to current flow varies as
a function of the state of the tissue. The attenuation of current
flow through tissues is a function of the biological properties of
the same as well as the frequency of the current. Normal and
pathological states demonstrate different impedance profiles. The
presence of or changes in these profile(s) correlate with different
physiological states. Additionally, the penetration of AC currents
is frequency dependent. So, for a given case, such as searching for
hematomas post-surgically, an appropriate selection of frequencies
should yield the ability to "look" deeper or shallower in the
tissue.
[0027] Whether provided as described in the above-reference
patent(s) or otherwise, a current or voltage generating means is
coupled to the sensor members for use. In addition, voltage or
current detecting means may be coupled thereto, or a specially
adapted impedance sensing means may be utilized in connection with
the impedance sensor members.
[0028] A distal end 10 of each lead or probe may directly contact
body tissue or it may be in electrical contact with the body via
pads, caps or another intermediate interface member. The same is
true for the other sensors disclosed herein. Some part may be
placed in direct contact with a user or an intermediate layer of
material or member may be present. Especially in connection with
temperature sensors, any such structure preferably enjoys a high
thermal conductivity or is at least so thin that it interferes
little with patient temperature sensor readings.
[0029] FIG. 1B shows a first type of temperature sensor that may be
used. A thermocouple 12 is shown. A thermocouple is provided by a
junction 14 between two dissimilar metallic conductor leads 16 and
18. A proximal end 20 of each lead connects the thermocouple to
appropriate hardware for use.
[0030] The junction between the two metals generates a voltage
which is a function of its temperature and the type of metals
employed. The temperature at the junction can be determined by
measuring the voltage via leads connected to appropriate hardware
in reference to tabular data or by using various algorithms
describing a given thermocouple's performance. While most
thermocouple types are appropriate for use in the present
invention, T, J or K-type devices may be preferred because of their
common nature and/or relative stability in temperature measurement.
Of course, the construction and operation of thermocouples is
well-known in the art.
[0031] Another sort of temperature sensor that may be employed in
the present invention is commonly known as a thermistor. A
thermistor is a semiconductor device that senses and detects
temperature by measuring electrical resistance. The silicon
material of which a thermistor is typically made has a resistance
that varies with temperature due to the semiconductor material's
high temperature coefficient of resistance. FIG. 1C shows a
disk-shaped thermistor 22 that may be used in the present
invention. Ends 20 of leads 16 and 18 connect the thermistor to
appropriate hardware for use. The fabrication and operation of
thermistors is also well known in the art.
[0032] Still other types and/or formats of temperature sensor
members may be employed. For instance, junction-based thermal
sensors (e.g., diode or transistor temperature sensors),
thermopile, fiber optic detectors, acoustic temperature sensors,
quarts and other resonant temperature sensors, thermo-mechanical
temperature sensors or thin film resistive elements may also be
used. Detailed discussion of many of these devices is presented in
the "Micromachined Transducers Sourcebook," by Gregory T. A.
Kovacs, published by McGraw-Hill 1998. Other information regarding
the sensors is well known in the art.
[0033] With respect to any of the temperature sensors (those named
and others known in the art), any of their common configurations
may be employed even though only certain examples are illustrated
in the figures. For example, though FIG. 1C shows a disk-shaped
thermistor 22, other suitable common thermistor configurations
include ceramic beads, chips, rods, washers, glass encapsulated
beads, etc.
[0034] Based on the type(s) of temperature sensor selected, certain
collateral hardware may be required. While colorimetric temperature
sensors are self-contained and can be read without the aid of
equipment, the same may not true for all other types. One with
skill in the art will easily appreciate what sort of equipment need
be connected or coupled to the temperature sensors for taking
measurements or detecting a temperature difference between at least
two sensors. Further, the manner in which electronic memory may be
coupled to store or record data taken to assist in diagnosis will
be readily apparent.
[0035] Regarding such hardware that may be provided in connection
with temperature sensors (or impedance sensors as discussed above),
it may be provided in stand-alone system or monitor that the
sensors (or a buss which the sensors are connected to) mate with.
Alternately, some or all of the hardware may be packaged with the
sensors and the support structure selected. Another possibility is
that a portion of the hardware that is used for data acquisition or
interpretation is packaged with the sensors and the remainder
resides at a stand-alone location. Either a physical connection or
remote/telemetry type connection may be employed in this regard
which the present invention is connected to directly or via some
form of remote connection.
[0036] RF signals sent and received by first and second telemetry
units, respectively may be employed. An exemplary system applicable
to such use is disclosed in U.S. Pat. No. 6,083,174 to
Brehmeier-Flick. Other telemetry units and applications thereof
well known in the art are also applicable to the present
invention.
[0037] Regardless, transmission of data to other diagnostic and/or
data storage device(s) may be carried out in burst or continuous
fashion as described variously. Telemetry for use in the home is
contemplated. In the case of a hospitalized patient, telemetry of
data to a central Intensive Care Unit (ICU) station provides
another example of use.
[0038] In some variations of the invention, it will be preferred to
include a storage device attached to sensors directly to store data
indefinitely. Such an approach makes for a self-contained device
that can be periodically interfaced with a diagnostic
instrument.
[0039] Regardless of the configuration, data storage may
advantageously be used in connection with the sensor chosen in a
variety of ways. For instance development or resolution of an
impedance profile, stored over time, between at least a first and
second sensor members can signify a biological state of interest.
Examples of such states include the development or resolution of
absence of fluid or air collection, and the progress of tissue
swelling (immunologic proliferation), together with related
physiological changes. Further, storage of impedance data can
facilitate comparison of the measurements taken against a look-up
table or database to assist in diagnosis.
[0040] Still, an impedance profile generated between at least a
first and a second sensor member locations, at a particular
instant, may signify a biological state of interest. Examples of
such states include: 1) the presence or absence of fluid as in a
hematoma, inflammatory mass, abscess or infection; 2) the presence
or absence of air as in a pneumothorax; or 3) the presence of a
foreign body in tissue.
[0041] A number of useful observations can be made with respect to
stored temperature data as well. Both the development and/or
resolution of infection can be monitored (even deep to the skin)
through observation of stored sensor data. Additionally, the normal
(uninfected) healing of a wound may be observed. Just as infection
results in increased temperature of tissue, so does the healing
process, though generally to a lesser degree.
[0042] As normal wound healing progresses, wound temperature
decreases to baseline after about 72 hours. Accordingly, by
observing a return to normal temperature, an indication of
completed wound healing is available. Conversely, an observation of
continued elevation in temperature after 72 hours indicates the
presence of an infection. Where wound infection occurs, the
temperature remains elevated or climbs, usually over that of normal
(i.e., uninfected) tissues.
[0043] Other indications that may be observed through detection of
development or resolution of a temperature difference, over time,
between at least a first and second include monitoring a diagnostic
injection site for signs of immunological proliferation or
reactivity such as a TB tine test and monitoring the state of a
chronically inflamed tissue, including rheumatoid inflation or
other chronic autoimmune disease. Where temperature is measured
over a period of time, indication of a biological state may be
derived from temperature measurement parameters such as temperature
difference, or average temperature over a period of time. As with
monitors using impedance to observe biological states, temperature
data obtained over a period of time may be compared to a look-up
table or database. The use of such "categorized" data may be of
great assistance in drawing conclusions based on the data
obtained.
[0044] Still further temperature-based methods according to the
present invention involve determining pathological state of in view
of the presence or absence of a temperature difference between
tissue regions, at a particular instant. Examples of such
indications that may be detected in this manner include: 1)
vascular compromise to a tissue after trauma or in occlusive
vascular disease; 2) vascular compromise to a surgically modified
tissue such as an AV fistula for dialysis, or a reconstructive
muscular flap procedure or other procedure requiring vascular
anastomosis, or organ or tissue transplant; 3) detecting the
boundary of viable tissue after an insult such as after a severe
burn or frostbite, or after infection with tissue destroying
organisms such as clostridium perfringes; 4) in intraoperative
monitoring of tissue where direct application of energy may impart
excessive damaging heat such as during phacoemulsification of the
lens of the eye, or tympanoplasty of inner ear, or during
procedures involving eletrocautery or electrocoagulation, or during
procedures involving the administration of heated agents such as
high temperature chemotherapy, or thermal ablation of tumors; 5)
likewise, in intraoperative monitoring of tissue where direct
cooling may impart excessive damage to surrounding tissue such as
cryoablation of tumor; 6) in monitoring of tissue during procedures
for diagnosis or therapy such as intraoperative cardiac perfusion
monitoring or thermal dilution methods 7) in monitoring the state
of local anesthesia due to the administration of anesthetic agents,
or in the condition of sympathetic nerve block, or autonomic
dysfunction, and 8) immunological rejection of organ transplants.
For such indications, a temperature-based diagnosis may be achieved
by observation of a temperature rises/fall past a predefined limit
once or observation of a temperature rises/fall past a predefined
limit for a predetermined period of time. In addition, a diagnosis
may be made from observation of raised or lowered temperature at
one sensor location relative to a reference temperature sensor
location.
[0045] It is noted that in instances where temperature and
impedance are monitored over time (especially as facilitated by-
storage and processing of results) to make a diagnosis, that there
may be no need to seek a remotely-located reference against which
to compare wound temperature or impedance measurements. However,
especially with temperature-based systems according to the present
invention where instantaneous results are desired, a reference
measurement as well as a site-specific measurement is taken.
[0046] One type of sensor that lends itself to at-a-glance data
acquisition is a calorimetric temperature sensor 24. An example of
such a temperature sensor is shown in figure ID. Such colorimetric
temperature sensors are known.
[0047] The temperature sensor pictured includes a grid of
temperature-sensitive chemical indicators 30 deposited on a heat
transmissive backing 32. The breakdown of indicators and an
associated legend (not shown) or printing on the indicator panel
can be used to allow a user to properly read the temperature based
on the state of the indicator dots.
[0048] The indicators may be comprised of a layer of encapsulated
cholesteric liquid crystals, ortho-bromonitrobenzine,
ortho-chloronitrobenzine or materials such as those described in
U.S. Pat. No. 4,232,552 to Hof et al., although a variety of other
materials may also be used. Preferably, the composition selected is
such that upward and downward fluctuations in temperature are
registered in an instantaneous or near-instantaneous manner in
order to facilitate repeatedly checking the temperature of a
site.
[0049] FIG. 2A-2G show the various types of support members
mentioned above, with optional sensor member placement locations
indicated by arrows. In each of them, at least two sensor locations
are shown.
[0050] With impedance sensors, where two sensor locations are
provided, each location corresponds to the end of an electrical
lead 4. In such case, only one set of data (at a particular
frequency) is generated. With temperature sensors, where two sensor
locations are provided, separate or distinct temperature readings
are provided at each location to give comparative temperature
readings.
[0051] Of course, as illustrated in the figures, more that two
temperature sensors may be provided. Likewise, several impedance
sensors may be employed, instead of just one having a pair of
spaced-apart probes.
[0052] Hardware configured to include at least two sensor locations
is specifically adapted to the methodology contemplated by the
present invention and is therefore most preferred. Still, the
methodology described in connection with FIGS. 3-6 below may be
carried out otherwise. For instance, it may be carried out with
discrete sensors that are not carried by a single support
structure.
[0053] As for what is preferred, however, FIG. 2A shows a bandage
34 with spaced-apart temperature sensor locations 36 and/or
impedance sensor locations 38. The bandage preferably includes
adhesive sections 40 and a pad or gauze area 42.
[0054] For use in monitoring temperature, one sensor region 36 is
preferably centered on the bandage in order to register wound
temperature, whereas an adjacent sensor location 36 offers a
baseline temperature. The points where temperature readings are
taken should be separated by such a distance that a baseline
temperature reading from one sensor is unaffected or not
substantially affected by the temperature of whatever tissue that
the other sensor is positioned to monitor. Stated another way a
first sensor is set in proximity to undisturbed normal biological
tissue and at least a second sensor is mounted proximally to the
first sensor at the site of disturbed biological tissue, which was
subject to a traumatic incision or other action producing the
wound. Sensor separations of at least 1 cm may be approximate in
certain cases.
[0055] Yet, base-line temperature sensor(s) locations(s) should be
set so that temperature readings produced are properly comparable
to the site to be monitored. For example, when an external wound is
to be monitored according to the present invention, an adjacent
patch of skin will produce an appropriate baseline temperature for
comparison--whereas an internally taken temperature may not since
it will not be exposed to the same environmental conditions as the
site of interest that may cause temperature fluctuations.
[0056] The distance between impedance sensor members will also vary
from one application to another. It may depend on the form-factor
of the device(s) used or based on other factors. That is to say,
sensor member spacing will vary from case-to-case. Appropriate
spacing may be determined by those with skill in the art in view of
the particular issue faced.
[0057] For use in monitoring for sub-surface fluid accumulation,
preferred sensor element locations may differ from those employed
for temperature sensors. To use an impedance sensor most
effectively in monitoring a wound, the portion of its probes or
electrodes in electrical contact with a patient should straddle at
least a portion of the wound. Alternately, side-to-side,
top-to-side, or top-to-bottom placement of sensor members relative
to a wound, limb or other structure to be monitored may prove
effective, depending on the circumstances.
[0058] It is contemplated that the bandage or any other support
member as may be used in the present invention can be configured to
monitor both temperature and impedance. In which case, staggered or
spaced-apart sensor locations may be employed. Alternately, it may
sometimes be feasible to use a shared set of sensor locations.
[0059] FIG. 2B shows a simple strip 44 serving as a support member.
The strip may be a polymeric member or made of another material. It
includes various sensor placement locations 36 and 38. Such a
support device is optionally retained by a patient through the use
of tape 46 or adhesive 48 applied to a the skin.
[0060] FIG. 2C shows a patch or plate 50 as may be used as a
support member. It may comprise a cotton or synthetic or fabric,
alternately it may be made of foam, a flexible polymer or a
corrosion resistant metal such as titanium. Generally, it is
preferred to use support members that are not substantially
thermally conductive. It may cover a larger area and include a grid
or matrix of sensor locations 36/38. It may be affixed to a patient
by tape, another fixative or otherwise. Further, it may be
implanted.
[0061] Instead of affixing or adhering a sensor support structure
to a patient, it may be retained by a patient or subject otherwise.
FIG. 2D shows a sensor support sleeve or cuff 52. It too includes a
plurality of sensor locations 36/38, placed as may be suitable for
detecting the temperature at one or more monitoring sites and one
or more reference locations or impedance at one or more sites. Such
sensing may be at opposite sides of the sleeve. A sleeve can be
expanded to fit over a digit or appendage and remain situated by
elastic material incorporated into a portion of the sleeve or the
entire device.
[0062] Yet another approach for a sensor support to be worn by a
user is presented by the use of a wrap 54 as shown in FIG. 2E.
Sensors locations 36/38 are shown adjacent one end. However any
sort of convenient placement may be selected. Elastic wraps or
wraps made of non-elastic material may be employed.
[0063] Still further, a bracelet 96 may be utilized as a support
member. As shown in FIG. 2H, the bracelet may include an adjustable
interface 98. Various sensor location options are possible as with
the other devices described herein.
[0064] Further possible support members include, suction cup
member(s) 100/100' as shown in FIG. 2I. A singe suction cup may be
employed, or a plurality of associated members may be used. Any
convenient means may be employed to associate at a desired distance
or spacing such as a tie-bar 102 as shown. As to sensor location,
in a single-cup type system, a plurality of sensor members will be
associated or embedded in the structure. Where a multiple-cup
system is provided, each may include as few as a single sensor
location 36/38.
[0065] Additional examples of possible sensor support structures
also include prosthetic members 104. FIG. 2J illustrates prosthetic
knee components 106. As in the preceding examples, sensor locations
36/38 may be located variously.
[0066] FIG. 2F shows an example of a sensor support in the form of
a shunt or graft tube 56. Typically, a shunt is little more than a
conduit attached between two natural body fluid pathways to
redirect flow or provide access to a given flow path. An exemplary
shunt application is hemodialysis, usually between the radial
artery and cephalic vein. Shunts find use in other applications as
well, such as in communicating blood from a patient's aorta to
pulmonary artery as illustrated in FIG. 5. A plurality of sensor
locations are shown along the body of shunt 56.
[0067] FIG. 2G shows a drain or catheter 58. As with shunts, such
devices may take various forms. Drains are typically used to
evacuate or establish an exit route for fluids or purulent material
from any cavity or wound. Infusion catheters are often used to
deliver drugs for thereby. An end section of a perforated drain or
catheter is shown. Orifices 60 conduct fluid to or from a central
lumen 62. Of course, other drain or catheter configurations may be
used in the invention. Multiple-lumen designs are common. To infuse
drugs or fluid irrigants, device 58 may be connected to a pump. To
assist in evacuation of fluid, the device may be connected to
suction. Either action is indicated by the double-arrow in FIG.
2G.
[0068] At a point upstream from the section shown in hatching, the
drain or catheter exits the body, through the wound itself that is
being monitored or through remote stab incision. Temperature and or
impedance sensors are preferably provided at locations 36/38 in the
region of the implanted portion of device 58 since sensors in this
region will be capable of producing useful data.
[0069] Indeed, sensor members according to the present invention
may be incorporated in any sort of implantable or semi-implantable
device such as those described above, variations of certain devices
(e.g., the catheter may be configured as a urinary and cardiac
catheter), or other implant prosthesis devices. The manner in which
implantable or semi-implantable support structures according to the
present invention are retained by a patient may vary. A shunt may
be secured using common techniques such as suturing. The length of
a drain is usually held in place largely by virtue of its location,
while its external portion is secured by suture(s) or tape to a
patient's skin.
[0070] Both the drain or catheter and shunt advantageously include
temperature and impedance sensors. Combined ability to sense for
infection and fluid volume has particular applicability with these
variations of the present invention. High incidents of infection
are often associated with implants, especially those with partial
external exposure.
[0071] Actually, fluid-sensing capability of the present invention,
when employed in shunts, grafts, infusion catheters and drains (and
the like) offer the ability to monitor the efficacy/function of the
devices. Accumulation of fluid (or the lack thereof) may indicate
clogging, misplacement or another malfunction.
[0072] With implantable or semi-implantable variations of the
invention, the sensors types included in FIGS. 1A-1C are preferred.
Each of these sensor types is readily monitored remotely by
electronic means while the device is in situ.
[0073] It is contemplated that other types of electronic sensors
may be incorporated in such devices as well (e.g., sensors able to
detect biochemicals associated with healing. Further, sensors as
described above that are able to detect particular bacteria may be
employed.
[0074] Whatever the type of sensor employed, it is contemplated
that the manner in which sensors are carried by any of the various
sensor support structures disclosed may be varied. Where laminate
constructions are preferred, sensors may be located between layers.
Of course, sensors may be surface-mounted on the respective support
structures. Other times, they will be set at their respective
locations within the body of the support structure.
[0075] In instances where a layer of material is provided between a
given sensor member or a portion of a sensor, this layer should be
conductive. With respect to thermal or temperature sensors, the
material should at least be thermally conductive, rather than
insulative. With respect to impedance type sensors, the material
should at least be electrically conductive, such as conductive
electrolyte gels, polymers or pastes or fabrics impregnated with
such conductive or semi-conductive materials.
[0076] Particular hardware configurations for practicing methods
according to the present invention are shown in FIGS. 3-6. In FIG.
3, a patient's forearm 64 is shown wearing an external monitor 66
according to the present invention over a wound 68. In this very
basic variation of the invention, a bandage 34 is affixed to the
skin of a patient by adhesive regions 40. First and second
temperature locations 36 include (or are filled by) colorimetric
temperature sensors 24.
[0077] The temperature of the wound and the temperature of an
adjacent location is registered via the sensor patches 24 while
monitor 66 is in place. Accurate temperature readings are obtained
by thermal conductance through the sensor backing or any
intermediate support layers. By checking the status of the sensors,
the status of the wound may be determined.
[0078] When a sensor more amendable to electronic monitoring is
used (such as those in FIGS. 1A-1C), checking the status of a wound
or another site of interest may be done automatically, including
signaling values beyond a desired range. Such an approach may be
easily implemented with hardware and software as readily apparent
to one with skill in the art.
[0079] FIG. 4 shows a bandage including spaced apart impedance
sensor members/leads/terminals 4 in connection with a patient's arm
64. Ends 10 of each impedance sensor member are set at locations 38
straddling wound 68.
[0080] With impedance sensing (preferably on either side of the
wound), by using various data processing techniques, the status,
including location of a region of fluid accumulation 70 beneath the
skin can be detected. Such processing may be accomplished by
hardware (and any associated software or logic) which the sensor
leads are connected to. Alternately, certain hardware may be
provided by on-board hardware 72 carried by the sensor support
member. The same is true in situations where temperature sensors
are employed or where both temperature sensors and impedance
sensors are employed.
[0081] Any such on-board hardware may include power supplies,
memory, microchip processors and/or telemetry units. Memory may be
used to record data for later analysis and/or store programming to
run included hardware. A telemetry section of the on-board hardware
may be included to avoid the need to make a physical connection
with external hardware to obtain or retrieve data
[0082] FIG. 5 shows another monitor employing self-contained
hardware. Here a shunt 56 is shown attached between a patient's
aorta 74 and pulmonary vein 76. Impedance sensors probes 10 are
provided at spaced apart locations 38 along the device to monitor
the surrounding area to give an indication whether the device it
remains open and situated to properly pass blood between the
anatomical structures.
[0083] A hardware support packet 78, including circuitry for
measuring impedance, a telemetry unit and such other features as
desirable is provided in the variation of the invention shown in
FIG. 5. It is provided separate from the shunt, but connected via
electrical leads 80. The location of the hardware may be remote
from the sensors, yet fully implanted to minimize issues associated
with infection. By implanting it near the surface of the skin, a
counterpart unit 82 may be readily employed with inductive
interface to recharge packet 78. Implanting such a packet near the
skin 84 of a patient or subject's body also reduces the power
requirements of telemetry units used to transmit data acquired by
the monitor to external hardware.
[0084] FIG. 6 illustrates the use of another type of monitor and
methodology according to the present invention. Again a patient's
forearm 64 is shown in connection with a wound 68. A drain or
catheter 58 is inserted through a stab 86 in the arm to release or
evacuate fluid 70 from a cavity 88 below the wound entry.
Alternately, access to the cavity 88 may be had through the wound
incision.
[0085] The drain includes both temperature and impedance sensors
located at intervals along the body of the device. Thermisors or
thermocouples are equally preferred for use as the temperature
sensors. Lead wires 80 from the sensors are preferably included in
the device body 90 for connection to support hardware. This
preferred relation is shown magnified at a section taken in the
device.
[0086] Such lead wires interface with hardware that preferably
regularly monitors the temperature status and/or impedance provided
by the sensors. Certain programming to sound an alert or take
remedial action such as to increase or adjust suction from a drain,
prompt adjustment of the shunt or increase the rate of drug
delivery from a catheter may be employed in response to data taken
from such monitors and others according to the present
invention.
[0087] In many instances, the programmed action for hardware in
association with any of the monitors will be to make and display a
diagnosis based on sensor results. The type or nature of any such
diagnosis and/or display may be of the sort referenced herein, in
any of the documents incorporated by reference or otherwise. A
monitor display 92 as shown in FIG. 5 (but optionally incorporated
in other hardware) is preferably provided so that complex messages
or instructions can be communicated to a user or a physician.
Alternately, a simple indicator 94 such as a light emitting diode
as included in the hardware in FIG. 4 may be provided to light up
or change color to indicate a condition relating to sensor results.
Hardware to sound an audio alarm or provide audio instructions to a
user of a monitor according to the present invention may also be
provided.
[0088] In addition to (or instead of) providing alarms or user
instructions, the monitors may be programmed and include such
hardware or be interfaced with such equipment as to allow it to
direct remedial action. That is to say, monitors according to the
present invention may activate secondary devices to perform therapy
such as deliver therapeutic medications after triggered by an
impedance change or profile or a temperature change or profile.
[0089] It is contemplated that various features of each of the
embodiments shown may be used with another. Furthermore,
methodology most preferably carried out with the variations of the
invention disclosed may be carried out otherwise. For example it is
contemplated that temperature sensors used to make comparative
temperature readings need not be-carried by or be integral with a
single support member. Especially for variations of the invention
taking internal temperature readings, obtaining a reference
temperature at an area far remote from an area to be monitored or
studied may even be preferred. Still, including multiple
temperature sensors along the length or surface of an internal
monitor according to the present invention can provide advantages
in terms of pinpointing infection or inflammation such as in
transplant rejection or autoimmune diseases such a rheumatoid
arthritis in relation to any portion of the device.
[0090] Further, as noted above, methods according to the present
invention using repeated temperature sensing are not limited to
monitoring wounds but also include monitoring the state of locally
anesthetized tissue, blood flow to muscle flaps or skin, tissue
affected by burns, frostbite or immunologic rejection of organ
transplants. The status of each indication is linked to blood flow
and, hence, the temperature which the tissue will present at. With
respect to producing systems for monitoring any of the latter
indications that may recede or advance, a number of individual
temperature sensors may be aligned in a series, grid or matrix as
shown in connection with the sensor support in FIG. 2C to allow
tracking of the situation.
[0091] In addition, the present invention is applicable to
situations where the patient to be monitored is a viable fetus. For
example, a monitor may be affixed to or retained by a subject of
fetal surgery. Also, monitoring (especially impedance-based
monitoring) may be used to guard against hydronephrosis, involving
fluid accumulation and pressure build-up on the kidney or
interuterine conditions such as oligohydramnios or
polyhydramnios.
[0092] Additional potential applications of aspects of the present
invention--and background regarding those mentioned above--are
described in connection with the following writings: Stein, L. E.,
et al., A comparison of steady state and transient thermography
techniques using a healing tendon model Veterinary Surgery, 1988.
17(2): p. 90-6.; Horzic, M., K. Maric, and D. Bunoza, The
temperature dynamics during the healing processing of a surgical
wound. Biomed Tech (Berl), 1995. 40(4): p. 106-9.; Viitanen, S. M.
and J. Viljanto, Wound healing. A thermographic study. Annales
Chirurgiae et Gynaecologiae Fenniae, 1972. 61(2): p. 101-6.; Kiot,
D. A. and S. J. Bimbaumn, Thermographic studies of wound healing.
American Journal of Obstetrics & Gynecology, 1965. 93(4): p.
515-21.; Horzic, M., D. Bunoza, and K Maric, Three-dimensional
observation of wound temperature inprimary healing. Ostomy Wound
Manage, 1996. 42(8): p. 38-40, 42-4, 46-7.; Horzic, M., D. Bunoza,
and K. Maric, Contact Thermography in a study of primary healing of
surgical wounds. Ostomy Wound Management, 1996. 42(1): p. 36-8.;
Waterman, N. G., L. Goldberg, and T. Appel, Tissue temperatures in
localized pyogenic infections. American Journal of Surgery, 1969.
118(1): p. 31-5.; Golbranson, F. L., E. G. Yu, and R. H. Gelberman,
The use of skin temperature determinations in lower extremity
amputation level selection. Foot & Ankle, 1982. 3(3): p.
170-2.; Stoner, H. B., L. Taylor, and R. W. Marcuson, The value of
skin temperature measurements in forecasting the healing of a
below-knee amputation for end-stage ischaemia of the leg in
peripheral vascular disease. European Journal of Vascular Surgery,
1989. 3(4): p. 355-61.; Sandier, D. A. and J. F. Martin, Liquid
crystal thermography as a screening test for deep-vein thrombosis.
Lancet, 1985. 1(8430): p. 665-7.; Gaiziunas, A. G. and M. H. Hast,
Temperature gradients and prediction off lap viability. Journal of
Otolaryrgology, 1976. 5(5): p. 399-402.; Holnstroom, H.,
Temperature changes of woundfluid inbipedicle tubeflaps. An
experimental study. Scandinavian Journal of Plastic &
Reconstructive Surgery, 1973. 7(2): p. 102-4.; Hackett, M. E., The
use of thermography in the assessment of depth of burn and blood
supply of flaps, with preliminary reports on its use in Dupuytren's
contracture and treatment of varicose ulcers. Br J. Plast Surg,
1974. 27(4): p. 311-7.; Frank, S. M., et al., Temperature
monitoring practices during regional anesthesia [see commenis].
Anesthesia & Analgesia, 1999. 88(2): p. 373-7.; Park, E. S., et
al., Comparison of sympathetic skin response and digital infrared
thtermographic imaging in peripheral neuropathy. Yonsei Medical
Journal, 1994. 35(4): p. 429-37.; Palmer, J. B., et al., A cellist
with arm pain: thermal asymmetry in scalenus anticus syndrome.
Archives of Physical Medicine & Rehabilitation, 1991. 72(3): p.
237-42.; Pogrel, M. A., C. McNeill, and J. M. Kim, The assessment
of trapezius muscle symptoms of patients with temporomandibular
disorders by the use of liquid crystal thermography. Oral Surgery,
Oral Medicine, Oral Pathology, Oral Radiology, & Endodontics,
1996. 82(2): p. 145-51.; Robiesek, F., et al., The application of
thermography in the study of coronary blood flow. Collected Works
on Cardiopulmonary Disease, 1979. 22: p. 49-56.; Robicsek, F., et
al., The value of thermography in the early diagnosis of
postoperative sternal wound infections. Thoracic &
Cardiovascular Surgeon, 1984. 32(4): p. 260-5.; Saxena, A. K, et
al., Thermography of Clostridium perfringens infection in
childhood. Pediatric Surgery International, 1999. 15(1): p. 75-6.;
Cole, R. P., et al., Thermographic assessment of burns using a
nonpermeable membrane as wound covering. Burns, 1991. 17(2): p.
117-22.; Ferguson, J. C. and C. J. Martin, A study of skin
temperatures, sweat rate and heat loss for burned patients.
Clinical Physics & Physiological Measurement, 1991. 12(4): p.
367-75.; Boylan, A., C. J. Martin, and G. G. Gardner, Infrared
emissivity of burn wounds. Clinical Physics & Physiological
Measurement, 1992. 13(2): p. 125-7.; Wyllie, F. J. and A. B.
Sutherland, Measurement of surface temperature as an aid to the
diagnosis of burn depth. Burns, 1991. 17(2): p. 123-7.; Mladick,
R., N. Georgiade, and F. Thome, A clinical evaluation of the use of
thermography in determining degree of burn injury. Plastic &
Reconstructive Surgery, 1966. 38(6): p. 512-8.; Lawson, R. W., G.
Webster, D., Thermographic Assessment of Burns and Frostbite. Can.
Med. Ass. J., 1961. 84: p. 1129.; Yamagami, S. and H. Yamagami,
Direct measurement of wound temperature during phacoemulsification.
Ophthalmologica, 1998. 212(1): p. 50-2.; Yamarnoto, K. and S.
Osako, Temperature and humidity in the surgical wound cavity
following tympanaplasty. Jibiinkoka, 1966. 38(11): p. 1165-9.
[0093] For many variations of the invention, at least a portion of
the inventive monitor is disposable or intended for one-time use.
Instead of attempting sterilization, discarding such portions of
the invention coming into contact with a patient may in many cases
be preferred or the only reasonable option.
[0094] It is to be understood that the invention is not limited to
the uses noted above or by way of the exemplary description
provided herein. The breadth of the present invention is to be
limited only by the literal or equitable scope of the following
claims. In construing the claims, any "support member" recited
shall not be construed according to 35 U.S.C. .sctn. 112, 6. Only
when referred to as a "means for sensor support" shall coverage
under .sctn. 112, 6 be invoked for the sensor support structures
disclosed. Likewise, only when the temperature and impedance
sensors disclosed are referred to as a "means for sensing" are they
(alone or in combination) to fall under .sctn. 112, 6.
* * * * *